Equity Changes in Accumulated Other Comprehensive Loss, Tax (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Apr. 03, 2021		Mar. 28, 2020		Apr. 03, 2021	Mar. 28, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		$ 2,382		$ 1,846		$ 2,380	$ 1,842
Other Comprehensive Income (Loss) before Reclassifications, Tax		(31)		17		7	39
Reclassification from AOCI, Current Period, Tax		(47)		(22)		(83)	(40)
AOCI Tax, Attributable to Parent, Ending Balance		2,304		1,841		2,304	1,841
Accumulated Net Gain (Loss) from Market Value Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		95	[1]	5	[1]	40	(29)
Other Comprehensive Income (Loss) before Reclassifications, Tax		(24)	[1]	(51)	[1]	22	(31)
Reclassification from AOCI, Current Period, Tax		(2)	[1]	10	[1]	7	24
AOCI Tax, Attributable to Parent, Ending Balance	[1]	69		(36)		69	(36)
Unrecognized Pension and  Postretirement Medical  Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		2,155		1,724		2,201	1,756
Other Comprehensive Income (Loss) before Reclassifications, Tax		(13)		10		(14)	10
Reclassification from AOCI, Current Period, Tax		(45)		(32)		(90)	(64)
AOCI Tax, Attributable to Parent, Ending Balance		2,097		1,702		2,097	1,702
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Tax, Attributable to Parent, Beginning Balance		132		117		139	115
Other Comprehensive Income (Loss) before Reclassifications, Tax		6		58		(1)	60
Reclassification from AOCI, Current Period, Tax		0		0		0	0
AOCI Tax, Attributable to Parent, Ending Balance		$ 138		$ 175		$ 138	$ 175

[1] Primarily reflects market value adjustments for cash flow hedges.